Bacteriologic culture apparatus



Nov. 20, 1962 H. KRAvlTz BACTERIULOUIC CULTURE APPARATUS Filed NOV. 2l, 1960 ATTORNEYS.

United States Patent tice 3,065,150 Patented Nov. 20, 1962 3,065,150 BACTEROLOGIC CULTURE APPARATUS Harvey Kravitz, 9243 Avers Ave., Skokie, Ill. Filed Nov. 21, 1960, Ser. No. 70,510 Claims. (Cl. 19E- 139) This invention relates generally to culture dishes of the type utilized in the cultivation of bacterial organisms and more particularly to new and improved Petri dish apparatus for facilitating the study and identification of such organisms on solid culture media.

It is of prime importance in the practical study of bacteria that these organisms can flourish in the laboratory in artificial food media. Such growth is designated a culture, and, in general, it is easily visible to the naked eye within a day or two under suitable conditions. On a solid culture media, growths of particular species may present a characteristic morphology. When individual -bacteria are sufficiently separate from one another,

streaked in colonies on the surface of a solid medium, a visible colony of growth results from each viable cell. l ust as the bacterial cells of a species may possess a characteristic morphology, so also do these bacterial colonies show special morphological features, and these are often significant in the identification of the pathogenic and commensal organisms.

Those skilled in the medical and biological arts are familiar with this practice of culturing or streaking out a plate in a Petri dish. Normally, the culture medium in the Petri dish is streaked, as by a suitable wire loop or cotton swab, to progressively dilute the amount of bacteria on the loop or swab, which bacteria may be derived from a specimen of a patients secretion. Whether the streaking be attempted at the patients bedside, in the doctors otlce or in the laboratory, it will be appreciated that considerable skill is often required to streak a plate in a desired pattern `so as to provide a maximum number of individual colonies for ecient bacterial isolation and identification and enumeration.

For example, such streaking out of a plate is a learned technique which has not been standardized and which varies considerably from person to person. Often, it is excessively time consuming and requires extra equipment such as a platinum or chrome wire loop and alcohol. If the streaking is not performed in a proper manner, maximum dilution may not be ensured and, in addition, a cutting or partial destruction of the culture medium may result. Due to the several limitations, streaking is a diicult bedside procedure, and usually requires more extensive facilities wherein the specimen taken from the patient is brought to the oce or laboratory.

Since a poorly streaked plate is practically Worthless, it is an object of this invention to provide new and improved Petri dish apparatus which is characterized by both its simplicity of use and its high degree of efficiency.

In accordance with the `features of one illustrative embodirnent of the invention, the improved culture apparatus comprises a generally iiat covered receptacle containing a suitable culture medium, such as a blood agar, therewithin, in the general form of a well-known Petri dish. In addition to the standard features of prior art Petri dishes, the invention further comprises a semi-rigid disc of a high grade non-porous paper or plastic material which has the property of adhering to the culture medium when the disc is placed thereon. Advantageously, the disc is provided with a plurality of elongated narrow slits so as to form a template capable of facilitating the streaking of the culture medium by a bacteriologic specimen.

The slits are formed in a parallel spaced-apart pattern, in accordance with the desired lstreaking pattern, and preferably the slits are made of a width just suicient to permit bacteria to streak the culture medium when a specimen containing swab or loop is inserted in the slits.

Thus, it is a further object of this invention to provide a template disc for use with a Petri dish wherein said template disc is formed `with a plurality of narrow slits corresponding to a desired streaking pattern of the culture medium in the Petri dish.

lt is n further object of this invention to provide new and improved culture apparatus, as described above, which eliminates the disadvantages of prior art timeconsuming and erratic methods, and which permits streaking of a culture medium to be obtained in a quick, simple and uniform manner.

It is a still further object of this invention to provide an improved template disc for use with a Petri dish as described above, which is'of relatively simple and inexpensive construction.

It is another object of this invention to provide a new and improved template disc adapted to be positioned on the culture medium within a Petri dish which permits the Petri dish to be utilized as a cough plate in the analysis of whooping cough and other similar diseases.

It is still another object of this invention to provide a new and improved culture apparatus including a template disc which facilitates the quantitative measure of the bacteria count in the air by exposing only predetermined portions of the culture medium to the air.

It is still another object of this invention to provide a new and improved culture apparatus as above which utilizes a unique template disc for maximizing the distribution of the bacteriological specimen on the culture medium to ensure the growth of an optimum number of individual colonies thereon.

It is still another object of this invention to provide a new and improved template disc for use with a Petri dish which is characterized by its el'liciency, flexibility, and labor-saving features.

The novel features which are characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following description taken in conjunction with the accompanying drawings in which:

FIGURE l is an exploded view of one illustrative embodiment of the invention comprising a culture medium containing Petri dish together with cover therefor and a novel template disc useful in facilitating the streaking process;

FIGURE 2 is a plan view, partly broken away, illustrating the streaking relationship of the Petri dish, the culture medium and the template disc;

FIGURE 3 is a cross-sectional View showing the guiding function of the template disc in facilitating the streaking of the culture medium by a wire loop;

FIGURE 4 is an end View of FIGURE 3 showing the wire loop streaking the culture medium; and

FIGURE 5 is an end cross-sectional view showing multiple streaking of the culture medium by a passage of a cotton swab over the template disc.

Referring now t-o the drawing, and more particularly to FIGURES l and 2 thereof, there is illustrated a preferred embodiment of the invention. As shown therein, this preferred embodiment comprises a Petri dish i0 of a well-known yand recognizable type. Thus, the Petri dish 10 may comprise a fiat base tray portion ll2 having an upstanding continuous wall 14 therearound so as to form a receptacle adapted to receive a layer of a suitable culture medium 16 therewithin.

As appreciated by those skilled in the art, the Petri dish advantageously may be formed of any suitable transparent plastic material, such as .polystyrene or the like,

having the characteristics of toughness, flexibility and resilience. The culture medium 16 may take any form suitable to the growth and propagation of micro-organisms, and illustrative forms include agar, Ibouillon and gelatin either plain or enriched with blood, tissue or dextrose.

In accordance with normal practice, the Petri dish is provided with a suitable cover 18 having a tlat base portion 20 with a continuous wall 22 extending therearound and depending therefrom. The dimensions of the cover 18 are chosen relative to the Petri dish 10 such that the wall 22 or cover 1S may be fitted telescopically over the upstanding wall 14 of the Petri dish to cover the culture medium 16 within the Petri dish. Advantageously, the cover 18 may be formed of a suitable transparent plastic material comparable to the material utilized in the Petri dish 10.

In accordance with a particular feature of this invention, streaking of the culture medium 16 within the Petri dish 10 is facilitated by means of a unique template disc 24 adapted to be positioned between cover 18 and dish 10 in contacting relation with the culture medium 16. In the use of Petri dishes `for a 'bacterial analysis, it is common to streak the bacterial specimen upon the culture medium in a plurality of spaced-apart, narrow rows such that the bacteria may develop in individual colonies whereby they may be observed at various intervals during their actual growth. Since the growth of a particular bacterial species on a solid culture medium may present a characteristic morphology, observation of such a growth facilitates the identification of the bacterial specimen.

Heretofore, such streaking of the culture medium has been performed in a rather undisciplined and non-uniform fashion. Proper streaking requires considerable skill and thus, valuable time of medical doctors and the like is often lost since the streaking cannot be delegated to untrained personnel. However, even a skilled person faces difficulties in streaking a culture medium due to the inconsistency of attempting to maximize the number of colonies by placing the streaks as close together as possible while at the same time, trying to prevent the streaks from touching or overlapping each other.

These difficulties are overcome in accordance wi-th the present invention through the use of the unique template disc 24. As clearly seen in FIGURES l and 2, the template disc 2e is provided with a plurality of parallel, spaced-apart, narrow slits 26 which expose corresponding slits of the culture medium. Preferably, the slits 26 are made sufficiently wide to permit the biggest bacteria to be streaked on the culture medium and in one preferable embodiment of the invention, the slits were made approximately three mils center to center.

As shown in FIGURE 1, the slits 26 may be provided on the template disc 24 in accordance with a desired streaking pattern. In one preferable `embodiment of the invention, the slits Z6 in the template disc 24 comprised three separate groups, namely, a first group 28 of elongated slits, a second group 30 of elongated slits parallel to the slits of group 28 but having a wider spacing therebetween, and a third group of slits 32 provided at right angles to the groups 28 and 30, and having a spacing approximately equal to the slits of group 30. This particularly advantageous streaking pattern has been found highly eicient in providing accurate and eflicient cultures.

In accordance with a further feature of this invention, the template disc 24 is provided with a relatively wide opening or cut-away portion 34 at one edge thereof. As shown particularly in FIGURE 2, the opening 34 exposes a relatively large portion of the culture medium 16 when the template disc 24 is positioned thereon. When the doctor, for' example, obtains a bacteriologic specimen from a patient, it is convenient for the doctor to coat the expo-sed portion of the culture medium 16 at the opening 34, as by swabbing, to temporarily store the specimen until the streaking operation can be performed. During the streaking operation, a sterile cotton swab or loop can be dipped into the `originally swabbed area at the exposed opening 34, and the specimen can then be streaked on the culture medium 16 through the slits 26 of the template disc 24.

This is illustrated in FIGURES 3 to 5. FIGURE 3 shows a wire loop passing through the slits 26 of the template disc 24 into contact with the culture medium 16. It can -be seen that the slits 26 provide a guiding function for the wire loop 36 such that the streaking is accomplished in a uniform predetermined pattern of narrow, parallel colonies. FIGURE 4 shows a specifically designed wire stylus 36, which is fitted into the slits of the template 24 to provide streaking of the culture medium 16. Those skilled in the art will lappreciate that the use of the guiding template disc 24 serves to provide better distribution of the bacteriologic specimen so as to maximize the colonies provided on the culture medium for further study and analysis.

rFiGURE 5 illustrates the use of a sterile cotton swab i0 in the streaking process. As there shown, the cotton swab 4.0 may be of sufficient size to provide multiple, simultaneous streaking of the culture medium 16, since portions of the cotton swab project through the various slits 26 of the template disc 24 into the culture medium.

In accordance with a still further feature of this invention, insertion Iand removal of the novel template disc 24 may be facilitated by means of a plurality of iinger receiving tabs disposed at the edges of the template disc 24.. For example, as Ashown in FIGURE l, a pair of fingerreceiving tabs 42 and t4 are provided at opposite sides of the template disc 24` and extend thereabove so as to be readily grasped when it is desired to remove the template disc Z4 from the Petri dish after the culture medium 16 has been streaked.

The streaking operation and the ready insertion and removal of the template disc 24 is enhanced when the template disc 24 is formed of a semi-rigid, high grade, nonporous paper or plastic material. Advantageously, the template disc 24 should be lflat to avoid any air bubbles between the template disc and the culture medium, and should be of a material enabling the template disc Z4 to closely adhere to the culture medium 16 as Well as to be readily released therefrom when the template disc 24 is lifted by means of the finger tabs 42 and 44.

lFurther, those skilled in the art appreciate that the ternplate disc and Petri dish combination of the invention is readily adaptable to many other advantageous uses. Por example, it may serve as a cough plate for whooping cough wherein the patient coughs directly on the template disc for directly streaking the culture medium exposed through the slits 26. In addition, the invention may be utilized to culture the air as by leaving the Petri dish open to the air with the template disc in place upon the culture medium. This would provide a desirable growth pattern rather than a random overgrowth which enables a better quantitative determination of the bacteria count in the air.

While there has been shown and described a specific embodiment of the present invention, it will, of course, be understood that various modifications and alternative constructions may be made without departing from the true spirit and scope of the invention. Therefore, it is intended by the appended claims to cover all such modifications and alternative constructions as fall within their true spirit and scope.

What is claimed as the invention is:

l. In combination with a Petri dish containing a bacteriologic culture medium, a cover for the dish comprising a relatively transparent plate having a shallow recess at the inner face thereof, and a template disc positioned between said Petri dish and cover in contacting relation with said bacteriologic culture medium, said template disc being formed with a plurality of parallel, spaced-apart, narrow slits for enabling said bacteriologic culture medium to be streaked with a bacterial specimen in a deaoeeneo sired pattern, said template disc further comprising a relatively large cut-away portion to expose the culture medium and to enable the bacterial specimen to be deposited thereon prior to the streaking operation and a plurality of linger receiving tabs disposed at the edges or" said disc and extending thereabove for facilitating the removal of said disc from the Petri dish after the streaking operation is completed.

2. In combination with a Petri dish containing a bacteriologic culture medium, a cover for the dish comprising a relatively transparent plate having a shallow recess at the inner face thereof, and a template disc positioned between said Petri dish and cover in contacting relation with said bacteriologic culture medium, said template disc being formed with a plurality of parallel, spaced-apart, narrow slits for enabling said bacteriologic culture medium to be streaked with a bacterial specimen in a desired pattern corresponding to said slits, said template disc further comprising a relatively large cut-away portion to expose the culture medium and to enable the bacterial specimen to be deposited thereon prior to the streaking operation.

3. ln combination with a Petri dish containing a bacteriologic culture medium, a cover for the dish comprising a relatively transparent plate having a shallow recess at the inner face thereof, and a template disc positioned between said Petri dish and cover in contacting relation with said bacteriologic culture medium, said template disc being formed with a plurality of parallel, spacedapart, narrow slits for enabling said bacteriologic culture medium to be streaked with a bacterial specimen in a desired pattern corresponding to said slits, said template disc further comprising at least one linger receiving tab disposed at an edge of said disc and extending thereabove for facilitating the removal of said disc from the Petri dish after the streaking operation is completed.

4. In combination with a Petri dish containing a bacteriologic culture medium, a cover for the dish comprising a relatively transparent plate having a shallow recess at the inner face thereof, and a template disc positioned between said Petri dish and cover in contacting relation with said bacteriologic culture medium, said template disc being formed with a plurality of parallel, spaced-apart, narrow slits for enabling said bacteriologic culture medium to be streaked with a bacterial specimen in a desired pattern corresponding to said slits.

5. In combination with a Petri dish containing a bacteriologic culture medium, a template disc positioned within said Petri dish in contacting relation with said bacteriologc culture medium, said template disc being formed with a plurality of narrow slits for enabling said bacteriologic culture medium to be streaked with a bacterial specimen in a desired pattern corresponding to said slits, and further having means for facilitating the removal of said disc from the Petri dish after the streaking operation is completed.

6. In combination with a Petri dish containing a bacteriologic culture medium, a cover for the dish comprising a relatively transparent plate having a shallow recess at the inner face thereof, and a template disc positioned between said Petri dish and cover in contacting relation with said bacteriologic culture medium, said template disc being formed with a plurality of parallel, spacedapart, narrow slits for enabling said bacteriologic culture medium to be coated with a bacterial specimen in a desired pattern corresponding to said slits for enabling the cultivation of individual bacterial colonies thereon, and

further having means for facilitating the removal of said disc from the Petri dish after the coating operation is completed.

7. The combination of a Petri dish containing a bacteriologic culture medium, and a removable template disc positioned within said Petri dish in contacting relation with said bacteriologic culture medium, said template disc being formed with a plurality of spaced-apart, narrow slits for enabling said bacteriologic culture medium to be streaked with a bacterial specimen in a desired pattern corresponding to said slits.

8. The combination in accordance with claim 7 wherein said removable template disc is formed of a semi-rigid non-porous material.

9. rPhe combination in accordance with claim 7 wherein said spaced-apart, narrow slits comprise a first group of parallel slits extending in one direction on said disc and a second group of parallel slits extending in a direction which is anvularly related to said rst group of parallel slits.

10. The combination in accordance with claim 7 wherein said removable template disc is formed of a flat nonporous plastic material.

Salle, A. I.: Fundamental Principles of Bacteriology, 1948, pub. by McGraw-Hill, New York, pp. ll34 and 135. 

1. IN COMBINATION WITH A PETRI DISH CONTAINING A BACTERIOLOGIC CULTURE MEDIUM, A COVER FOR THE DISH COMPRISING A RELATIVELY TRANSPARENT PLATE HAVING A SHALLOW RECESS AT THE INNER FACE THEREOF, AND A TEMPLATE DISC POSITIONED BE TWEEN SAID PETRI DISH AND COVER IN CONTACTING RELATION WITH SAID BACTERIOLOGIC CULTURE MEDIUM, SAID TEMPLATE DISC BEING FORMED WITH A PLURALITY OF PARALLEL, SPACED-APART, NARROW SLITS FOR ENABLING SAID BACTERIOLOGIC CULTURE MEDIUM TO BE STREAKED WITH A BACTERIAL SPECIMEN IN A DESIRED PATTERN, SAID TEMPLATE DISC FURTHER COMPRISING A RELATIVELY LARGE CUT-AWAY PORTION TO EXPOSE THE CULTURE MEDIUM AND TO ENABLE THE BACTERIAL SPECIMEN TO BE DEPOSITED THEREON PRIOR TO THE STREAKING OPERATION AND A PLURALITY OF FINGER RECEIVING TABS DISPOSED AT THE EDGES OF SAID DISC AND EXTENDING THEREABOVE FOR FACILITATING THE REMOVAL OF SAID DISC FROM THE PETRI DISH AFTER THE STREAKING OPERATION IS COMPLETED. 